What app could have allowed someone to hack another address book?

Recently I received a call from what looked like it was my daughter calling me. Her name and phone number showed up on my iPhone when the phone rang. I answered the phone and could hear back ground noise but no one said anything. I just figured she butt dialed me. A few minutes later i received a FaceTime from her. When I answered it was some kids who I've never seen before. One of them said "oh my gosh it worked." What app allows someone to hack another address book?